1. Field of the Invention
The present invention relates to the field of translation tubes affixed to the interior of outer space orbiting structures and space vehicles, generally known as space modules or space stations. In particular, the present invention relates to the integration of these translation tubes into expandable and inflatable space modules, such as the NASA TransHab module.
2. Discussion of the Prior Art
The cost of launching heavy structural components into space to build space stations and space vehicles is prohibitive. Intense research and development efforts have been expended into the development of lightweight structural components for these applications. In particular, internally pressurized, non-rigid, fabric-like, expandable structures have been found to provide significant weight savings over traditional space structure components. One of the most recently developed of these non-traditional space structures is NASA's TransHab space module.
These inflatable space modules use fabric-like materials to create non-rigid walls that can expand when pressurized, or otherwise expanded, to form the space module's pressure boundary. Typical materials used to form the TransHab module's walls include Nomex, Kevlar, and a variety of other fabric or sheet materials. Sponge like materials, such as open cell elastomers, are layered between these sheets. These elastomeric layers are compressed prior to launch. Once in orbit, the elastomeric layers are allowed to expand, the module is pressurized, and the space module expands into its deployed configuration. The elastomeric layers act to form the walls of the module and also provide insulation. Other means and materials are also available to form these expandable space structures. The present invention is particularly useful for application to any type of expandable space module with non-rigid, non-load bearing, pressure boundary walls.
The soft, non-rigid structure of inflatable space modules makes it difficult to outfit their interior space with life support and scientific equipment. The non-rigid design lacks structural hard points to anchor equipment, floors, docking ports, hatches, etc. Although designed for ultimate use in near weightless conditions, there is a critical need for equipment anchorage points to support equipment under earth gravity, and especially during launch. It is also imperative that the space module has rigid structural mounting points to maintain the relative positioning of equipment and materials even after the module is in orbit.
Besides equipment load stresses, the space module must also withstand internal pressurization forces caused by the inflation and pressurization of the space module once it is deployed in orbit. These forces vary dependent on the design of the space module. However, it is generally desirable, if not imperative, to restrain the space module to prevent overstressing the module's walls.
The space module may also experience stresses because of externally applied loads. For example, whenever the space module docks with a space vehicle, or another space structure, significant stresses are created. During these docking maneuvers, the space module's lack of structural rigidity may allow the pressure boundary to deflect, and overstress the space module. The space module must be reinforced to prevent this deflection, and protect the integrity of the space module during docking.
All of the above-described stresses, both internal and external, require the integration of a rigid internal framework into the space module to resist these loads. The internal framework must be designed to withstand these loads, rather than stressing the space module's walls. The development of this internal framework is dictated by the construction method employed to construct these inflatable structures.
One of the simplest methods for constructing these non-rigid structures involves forming a generally cylindrically shaped space module. The space module's fabric walls are gathered together to enclose, and form a cylinder at two connection points. Current construction practices utilize an end ring at both ends of the cylinder to form these connections, and complete the space module's pressure boundary. These end rings provide structural hard points on which to construct a rigid internal framework. The internal framework of prior art designs uses a translation tube that extends coaxially through the center of the cylinder, as exemplified by the NASA Transhab module.
The centric translation tube, however, has significant functional and structural drawbacks. The centric translation tube design disrupts the interior spatial distribution of the module, preventing the module's interior space from being effectively utilize. Many space module applications require a much greater uninterrupted volumetric space than can be provided by the current centric translation tube design. These applications require the use of oversized manufacturing and scientific equipment that simply cannot fit inside a space module with the centric translation tube design. The size of the space module is constrained by the size of the launcher's cargo bay volume, which is extremely limited. Consequently, the space module simply cannot be scaled up in size, to avoid the inefficiency of the centric translation tube.
The centric translation tube is also much more difficult to load with equipment and material during prelaunch activities. The centric translation tube only provides limited access to the inside of the translation tube. Not only is the centric translation tube difficult to load, deploying equipment once loaded the module is in orbit. Limited space is available to create portals through which to drag equipment. As a result, oversized equipment cannot be redeployed from the centric translation tube, limiting the flexibility of the space module.
Another significant problem associated with the centric translation tube is the space module's diminished habitability and livability. The crew quarters are always in close proximity to the centric translation tube. As a result, crewmembers that are passing through the translation tube are much more likely to disturb others who are sleeping, or concentrating on their work. Vibrations created by crew and equipment transiting through the translation tube may also affect space module experiments. Many types of scientific equipment are extremely sensitive to vibration (e.g., cameras, telescopes, etc.). The conduct of the experiments themselves may also be vibration sensitive, and adversely affected.
Finally, none of the current state of the art translation tubes used for inflatable space modules utilizes a separately pressurizable translation tube. This presents the potential for tragic consequences in the event of a breach of the space module's pressure boundary, or some other catastrophic failure occurs.
An improved translation tube is necessary to solve these problems. The limitations imposed by the prior art severely limits the mission capabilities of current space modules, and significantly increases the cost of many other missions. The centric translation tube is inefficient, and prevents the full utilization of inflatable space modules.